Lifting device

ABSTRACT

A device for lifting a load comprising a platform for supporting said load and a vertically extensible framework supporting said platform, said framework being formed from first and second pairs of spaced parallel vertically extensible members each member being formed from a plurality of interconnected sections and each said section being formed from a pair of cross levers pivotably connected at the center thereof and pivotably connected at the outer extremities thereof to the outer extremities of the cross levers of the next adjacent sections the outer extremities of the cross levers of each section of the first pair of members being also pivotably connected to the outer extremities of the cross levers of the corresponding sections of the second pair of members and a plurality of vertically spaced hydraulic rams disposed within said framework to act in a substantially vertical direction each hydraulic ram comprising a piston and a cylinder said piston being connected to said framework at the central pivot point of the cross levers of one of said sections and said cylinder being connected to said framework at the central pivot point of the cross levers of another section of said framework whereby to extend and retract said framework on actuation of said rams and means on the bottom of said framework adapted to move transversely of said framework on extension and retraction of said framework.

lJnite Laforest [4 1 Mar. 5, 1974 LllF'llING DEVICE [76] Inventor: Claude .1. Laforest, 189 A Lakeshore Ln., Timmins, Ontario, Canada [22] Filed: Jan. 23, 1973 [21] Appl. No.: 326,037

Related 0.8. Application Data [63] Continuation of Ser. No, 123,766, March 12, 1971,

abandoned.

[30] Foreign Application Priority Data Jan. 8, 1971 Canada 102246 [52] US. Cl 187/18, 254/122, 182/141 [51] Ilnt. Cl 1366b 11/64 [58] Field of Search 187/18; 254/122; 182/141 [56] References Cited UNITED STATES PATENTS 3,350,065 10/1967 Mankey 254/122 1,859,830 5/1932 254/122' 3,003,746 10/1961 Gridley 187/18 3,259,369 7/1966 Gridley 187/18 2,471,901 5/1949 Ross 254/122 0,682,083 9/1901 .lames 187/18 2,625,443 1/1953 Sensenbaugh 187/18 FOREIGN PATENTS OR APPLICATIONS 1,348,093 11/1963 France 254/122' Primary Examiner-Richard E Aegerter Assistant Examiner.leffrey V. Nase [57] ABSTRACT A device for lifting a load comprising a platform for supporting said load and a vertically extensible framework supporting said platform, said framework being formed from first and second pairs of spaced parallel vertically extensible members each member being formed from a plurality of interconnected sections and each said section being formed from a pair of cross levers pivotably connected at the center thereof and pivotably connected at the outer extremities thereof to the outer extremities of the cross levers of the next adjacent sections the outer extremities of the cross levers of each section of the first pair of members being also pivotably connected to the outer extremities of the cross levers of the corresponding sections of the sec .ond pair of members and a plurality of vertically spaced hydraulic rams disposed within said framework to act in a substantially vertical direction each hydrauvlic ram comprising a piston and a cylinder said piston being connected to said framework at the central pivot point of the cross levers of one of said sections and said cylinder being connected to said framework at the central pivot point of the cross levers of another section of said framework whereby to extend and retract said framework on actuation of said rams and means on the bottom of said framework adapted to move transversely of said framework on extension and retraction of said framework.

11 Claims, 11 Drawing Figures PATENTEDHAR 51w @IF'QEQQQ SHEET 3 BF 5 PATENTED W 5 74 SHEET t 0F 5 PATENTEU R 74 SHEET 5 BF 5 1 urrmcpsvtcr;

This is a continuation, application Ser. No. 123,766, filed, Mar. 12, 1971, now abandoned.

' The present invention relates to a lifting device for lifting loads and, in particular, the present invention relates to such a lifting device which is safe, stable, simple to operate and is capable of lifting a load, such as a man, to any preselected height in a short period of time. 7

Heretofore in the construction industry in order to work on the outside of a building it is conventional to erect scaffolding. vHowever, scaf-folding is expensive both in materials and labor and further, scaffolding takes a substantial time to erect and dis-assemble.

Lifting devices have also been proposed for raising loads to preselected heights based upon an extensible framework aided by various means including ratchets, pulley systems and hydraulic rams. Such lifting devices are disclosed for example in US. Pat. Nos. 3,174,722; 3,486,583;3,373,844;2,945,551;3,259,369;3,l60,228;- 2,l32,343;.2,706,102 and 1,095,391 as well as Canadian Pat. Nos. 307,991; 746,398; 802,749 and 93,864. However, the lifting devices proposed heretofore have usually been of complicated construction, expensive to manufacture, limited in their utility, particularly the height to which they are capable of raising a load and are subject to disadvantages with respect to safety.

Thus for example in U.S. Pat. No. 1,095,391 the platform for holding the load is raised by a ram between the base and the platform which gives the lifting device a very limited application in that the cost of the ram for lifting the platform to substantial heights is high; the weight of the cylinder and the oil required for such a ram is large, in the device of the US. Patent the framework merely stabilizes the cylinder and, as there is a single cylinder, failure of the-hydraulic system would collapse the lifting device and thus there is a safety factor problem.

The present invention provides a lifting device which is stable, safe, versatile, relatively cheap to manufacture, compact, relatively light and is capable of reaching substantial heights withoutthe aforesaid problems ofcost and weight. a

Ilt hasno'w been found" according to the present invention that the aforesaid lifting device may be obtained by providing a plurality of verticallyspaced hydraulic rams in such a framework asdisclosed in US. Pat. No. 1,095,391 with the pistonof each ram connected to the framework at the central pivot point of the cross levers of one of the sections of the framework and the cylinder connected to the central pivot point at the cross levers of another section, preferably an adjacent section of the framework.

According to the present invention, therefore, there is provided a device for lifting a loadcomprising a platform for supporting said load and a vertically extensible framework supporting said platform, said framework being formed from tirstand second pairs of spaced pan allel vertically extensible members, each member being formed from a plurality of interconnected sections and each section being formed from a pair of cross levers pivotably connected at the center thereofand pivotably connected at the outer extremities thereof to the outer extremities of the cross levers of the next adjacent section, the outer extremities of the cross levers of each section ofthe first pair of members also being pivotably connected to the outer extremities of the cross levers of the corresponding sections of the second pair of members, a plurality of vertically spaced hydraulic rams disposed within said framework to act in a substantially vertical direction, each hydraulic ram comprising a piston and a cylinder, said piston being connected to said framework at the central pivot point of the cross levers of one of said sections and said cylinder portion being connected to said frame at the central pivot point of the cross levers of another section thereof whereby to extend and retract said framework on actuation of said rams and means on the bottom of said framework adapted to move transversely of said framework while extension and retraction of said platform.

Thus, by the use ofa plurality of vertically spaced hydraulic rams connecting different sections of the framework it is possible to use substantially smaller rams to effect extension of the framework and at the same time due to the presence ofa plurality of hydraulic rams, the safety factor of the framework is increased for if one of the rams fails then there is at least one other ram operating to maintain the framework under extension. Pref erably the hydraulic rams are connected to adjacent sections of the framework thus allowing the hydraulic rams to have their" smallest length and thus provide a minimum height of the lifting device when the lifting device is in the fully retracted position.

In a preferred embodiment of the present invention, the lifting device includes a plurality, usually a pair of horizontally spaced hydraulic rams connected between theadjacent sections of the framework which again increases the safety factor and further provides for improved lifting capability of the framework of the device.

It is highly desirable that the lifting device in its fully retracted .position has the smallest height possible so that the platform can be readily loaded with the materials to be raised and in a particularly preferred embodiment of the present invention the plurality of hydraulic rams located within the framework are in offset positions such that when the framework is in the retracted position the hydraulic rams are located in horizontally spaced positions at the same leveladjac'ent the base of the framework, i.e. the hydraulic rams are nestable in side by side relationship adjacent the base.

The lower ends of the framework are suitably adapted to be movable on a base on extension and retraction of the framework as upon extension of the framework the lower ends of the framework will inherently move towards one another and vice versa on retraction of the framework. Suitably the ends of the framework are provided with runners adapted to move within channels extending diagonally in the base of the lifting device. The base of the lifting device may be suitably mounted upon a movable vehicle so that itmay be readily'pushed by two men to the desired location. It will be readily realized that for use in place of a scaffold, a pair of such lifting devices may be used in tandem, the platform being adapted to be extended from each of the lifting devices and connected together to bridge the gap between the spaced lifting devices.

In order on extension of the lifting device to begin extension of the framework, it is preferable to provide a booster hydraulic ram fixedly attached to the base of the lifting device and extending into abutment with the platform when said framework is in the retracted position. The present invention will be further illustrated by way of the accompanying drawings in which:

FIG. 1 is a side elevation ofa lifting device in the fully extended position according to one embodiment of the present invention;

FIG. 2 is a plan of the lower hydraulic ram system of the device of FIG. 1;

FIG. 3 is a side elevation of the lower hydraulic ram system of the device of FIG. 1; viewed in the direction of the arrow in FIG. 2;

FIG. 4 is a plan of the intermediate hydraulic ram system of the device of FIG. 1;

FIG. 5 is a side elevation of the intermediate hydraulic ram system of the device of FIG. I viewed in the direction of the arrow in FIG. 4;

FIG. 6'is a plan of the top hydraulic system of the device of FIG. 1;

FIG. 7 is a side elevation of the top hydraulic ram system of the device of FIG. I viewed in the direction of the arrow in FIG. 6;

FIG. 8 is a plan view of the base of the device of FIG. 1 which is identical witha view of the underside of the platform of the device of FIG. 1 except for the omission of the booster cylinder;

FIG. 9 is a side elevation of the device of FIG. 1 in its fully retracted position on a movable vehicle;

FIG. 10 is a schematic ofthe hydraulic system for operating the lifting device of FIG. 1; and

FIG. 11 is a schematic of the electrical system for operating the device of FIG. I.

Referring to the accompanying drawings, the lifting device comprises a base 1 and a platform 2 for supporting the load with a vertically extensible framework'3 therebetween. The framework 3 is four-sided, each side being formed from a plurality of pairs of cross levers 4 having a pivotable connection 5 at the center thereof and being pivotably mounted at' the extremities thereof in brackets 6. The lower and upper ends of the framework 3 have rollers 7 (see FIG. 8) mounted thereon which run in channels 8 in the base land also in the un derside of the platform 2 during extension and retraction of the framework 3.

The extension and retraction of the framework 3 is provided for by the lower hydraulic ram system 9, the intermediate hydraulic ram system 10 and the upper hydraulic ram system 11. Referring specifically to FIGS. 1, 6 and 7 the ram system 11 comprises an upper frame 12 formed from steel plate, the frame being welded to rods 13 and including gusset plates 14 for reinforcement of the frame and a lower frame 15 also formed from steel plate and welded to rods 16, the frame I5 also including gusset plates 17 for reinforcement thereof. The rods 13 and the rods I6 slideably pass by means of bushings (not shown) through the pivot connections 15 of the cross levers 4 of adjacent sections of the framework 3. The rams I8 of the ram system II have the piston rods 19 thereof pivotably connected by means of pivots 20 to the upper frame 12 and the cylinders 21 thereof pivotably connected by means of pivots 22 and links 23 to the lower frame 15.

Referring to FIGS. I, 4 and 5 the intermediate hydraulic ram system I0 generally comprises an upper frame 24 formed of steel plate and welded to rods 25, the frame 24 including gusset plates 26 for reinforcement thereof and a lower frame 27 also formed from steel plates and including gusset plates 29a for reinforcement thereof welded to rods 28. The rods and rods 28 similarly slidably pass by means of bushing (not shown) through pivot connections 5 of the cross levers 4 of adjacent sections of the framework 3. The rams 29 of the hydraulic ram system 10 have rods 30 pivotably connected by means of pivots 31 and links 32 to the upper frame 24 and cylinders pivotably connected by pivots 33 and links 34 to the lower frame 27.

With reference to FIGS. 1, 2 and 3 the lower hydraulic ram system 9 similarly includes an upper frame 36 of steel plate welded to rods 37, the frame 36 including gusset plates 38 for reinforcement thereof and a lower frame 39 also of steel plate and including gusset plates 41 for reinforcement thereof welded to rods 40. The rods 37 and slidably pass by means of bushing (not shown) through pivot connections 5 of the cross levers 4 of adjacent sections of the framework 3. The rams 42 of the hydraulic ram system 9 have rods 43 pivotably connected by pivots 44 and links 45 to the frame 36 and cylinders 46 pivotably connected by pivots 47 and links 48 to the frame 39.

In addition to the hydraulic ram systems 9, I0 and II thelifting device as shown in FIGS. 1 and 8 also includes a booster ram 49 comprising a cylinder 50 located in the base 1 of the device in a mounting socket 52 and a piston rod 51 which has located on the end thereof remote from the cylinder 50 a contact plate 51a which, when the framework 3 is in the fully retracted position with the piston 51 fully withdrawn, abuts the underside of the platform 2 and serves to initiate the extension of the framework 3, the ram 49 being actuated slightly before the rams 42, 29 and 18 in that order. The action of the ram 49 has the effect of inita lly unlocking the framework 3.

In FIG. 2 there is shown in outline the disposition of the rams I8, 29, 42 and 49 when the framework 3 is in the fully retracted position as in FIG. 9 from which it will readily be seen that the rams I8, 29, 42 and 49 are laterally disposed so as to be readily nestable such that the height of the platform is substantially the length of one of the rams. Further, it will be seen from FIGS. 1, 3, 5 and 7 that the location of the rams I8, 29 and 42 with respect to the rods to which they are connected also permits nestability of the ram on full retraction of the framework 3.

The rams I8, 29, 42 and 49 are actuated from a source set forthspecifically in FIG. 10 via hydraulic line 53 only a part of which is shown for the purposes of clarity which passes up the framework 3 along the cross levers 4 and is connected to the cylinders of the rams I8, 29 and 42 by conduits 54in the lower rods to which the cylinders of the rams are connected.

The rams I8, 29, 42 and 49 are actuated as shown in FIGS. I0 and II. On pressing the motor switch 55 on the board 56 (see FIG. I) of the platform 2 the motor 57 is actuated and operates pump 58 to pump hydraulic fluid from a tank 59 through a filter 60 and non-return valve 61 to the rams 49, 42, 29 and 18 in that order thereby extending the framework on pressing the solenoid switch 62 in the board 56 the directional oncway/one position valve 63 is opened to allow the hydraulic fluid to return to the tank 59. The hydraulic system is also provided with a pressure relief valve 64 and a manual relief valve 65. Further the orifice 68 at the cylinders 18, 29, 42 and 49 controls the flow of hydraulic fluid to and from the cylinders.

Referring to FIG. 9, the lifting device is suitably located on a movable vehicle or carrier frame 66 prosaid first and third pairs of cross-levers being spaced parallel and pivotably connected at the outer extremities thereof to the outer extremities of the second and fourth pairs of cross-levers which are also spaced and parallel, thereby to form said framework; lifting means disposed within each of said parts of the framework, each of said lifting means including a lower support frame and an upper lifting frame, said lower support frame being connected by means of links to the central pivot points of the four pairs of cross-levers forming a section of one part of the framework, and said upper lifting frame being connected by means of links to the central pivot points of the four pairs of the cross-levers forming another section of said one part of the framework said links being adapted to allow contraction and expansion of the framework; and a pair of vertically disposed hydraulic rams pivotably connected between said lower support frame and said upper lifting frame to cause, on actuation of said rams, displacement of the upper lifting frame relative to the lowersupport frame, to extend or retract the framework, said pair of rams being disposed at substantially equi-distant points on opposite sides from the center point of the framework and on either one of two centerlines diagonal to the framework, to provide balanced and equal distribution of actuated power to the central pivot points'of the four pairs of cross-levers forming said other section of one part ofthe framework; and means to allow the outer extremities of the pairs of cross-levers at the top and bottom of said framework to move diagonally with respect thereto when said framework is extended or retracted.

2. A device as claimed in claim 1 in which said pair of rams of each lifting means are disposed in offset positions relative to the location of the rams of the other lifting means, the rams of the said lifting means being arranged to accommodate the rams of the other lifting means such that on complete retraction of the framework said lifting means are disposed adjacent to each other and said rams are vertically disposed within each lifting means.

3. A device as claims in claim 1 wherein there are three interconnected parts of four sections including first, second and third lifting means and said pair of rams of each lifting means are disposedin offset positions relative to the location of the'rams of the other lifting means; the first lifting means being arranged to accommodate the rams of the second and third lifting means, said second lifting means being arranged to accommodate the rams of said first" and third lifting means, and said third lifting means being arranged to accommodate the rams of said first and second lifting means, such that on complete retraction of the framework said lifting means are disposed adjacent to each other and said rams are vertically disposed within each lifting means.

4. A device as claimed in claim 1 in which the hydraulic rams are connected between adjacent sections,

5. A device as claimed in claim 1 wherein said lower support frame and said upper lifting frame have four rod members extending through the central pivot points of four pairs of cross-levers forming one section of one part of the framework, said rods being adapted to allow contraction and expansion of the framework.

6. A device as claimed in claim 5 in which the rods are slideably mounted at the central pivot points of said four pairs of cross-levers.

7. A device as claimed in claim 1 in which said framework is located on the base and includes a booster hydraulic ram mounted on said base extending into abutment with said platform when said framework is in the retracted position.

8. A device as claimed in claim 7 in which the lower outer extremities of-the cross members forming the lower section of the framework are disposed on rollers arranged to move in diagonal channels across the base on extension and retraction of said framework.

9. A device for lifting a load comprising a platform fro supporting said load and a vertically extensible framework for supporting said platform, said framework being formed from a plurality of interconnected parts, eachsaid part of the framework being formed from a plurality of sections, and each said section being formed from first, second, third and fourth pairs of cross-levers pivotally connected at the center thereof, said first and third pairs of cross-levers being spaced parallel and pivotably connected at the outer extremities thereof to the outer extremities of the second and fourth pairs of cross-levers which are also spaced and parallel, thereby to form said framework; lifting means disposed within each of said parts of the framework, each of said lifting means including frame means connected to the central pivot points of pairs of crosslevers forming a section of one part of the framework, and to the central pivot points of pairs of the crosslevers froming another section of said one part of the framework said frame means allowing contraction and expansion of the framework; and vertically disposed ram means pivotably connected in said frame means to cause, on actuation of said ram means, vertical displacement in said frame means to extend'or retract the framework and means to allow the outer extremities of the pairs of cross-levers at the top and bottom of said framework to move diagnoally with respect thereto when ,said framework is extended or retracted.

10. A device as claims in claim 9 in which the frame means is connected to the central pivot points of opposite pairs of cross-levers forming a section of each part of the framework.

11. A device as claims in claim 9 in which the frame means is connected to the central pivot points of four pairs of cross-levers forming a section of each part of the framework. 

1. A device for lifting a load comprising a platform for suppOrting said load and a vertically extensible framework for supporting said platform, said framework being formed from a plurality of interconnected parts, each said part of the framework being formed from a plurality of sections, and each said section being formed from first, second, third and fourth pairs of cross-levers pivotally connected at the center thereof, said first and third pairs of cross-levers being spaced parallel and pivotably connected at the outer extremities thereof to the outer extremities of the second and fourth pairs of cross-levers which are also spaced and parallel, thereby to form said framework; lifting means disposed within each of said parts of the framework, each of said lifting means including a lower support frame and an upper lifting frame, said lower support frame being connected by means of links to the central pivot points of the four pairs of cross-levers forming a section of one part of the framework, and said upper lifting frame being connected by means of links to the central pivot points of the four pairs of the cross-levers forming another section of said one part of the framework said links being adapted to allow contraction and expansion of the framework; and a pair of vertically disposed hydraulic rams pivotably connected between said lower support frame and said upper lifting frame to cause, on actuation of said rams, displacement of the upper lifting frame relative to the lower support frame, to extend or retract the framework, said pair of rams being disposed at substantially equi-distant points on opposite sides from the center point of the framework and on either one of two centerlines diagonal to the framework, to provide balanced and equal distribution of actuated power to the central pivot points of the four pairs of cross-levers forming said other section of one part of the framework; and means to allow the outer extremities of the pairs of cross-levers at the top and bottom of said framework to move diagonally with respect thereto when said framework is extended or retracted.
 2. A device as claimed in claim 1 in which said pair of rams of each lifting means are disposed in offset positions relative to the location of the rams of the other lifting means, the rams of the said lifting means being arranged to accommodate the rams of the other lifting means such that on complete retraction of the framework said lifting means are disposed adjacent to each other and said rams are vertically disposed within each lifting means.
 3. A device as claims in claim 1 wherein there are three interconnected parts of four sections including first, second and third lifting means and said pair of rams of each lifting means are disposed in offset positions relative to the location of the rams of the other lifting means; the first lifting means being arranged to accommodate the rams of the second and third lifting means, said second lifting means being arranged to accommodate the rams of said first and third lifting means, and said third lifting means being arranged to accommodate the rams of said first and second lifting means, such that on complete retraction of the framework said lifting means are disposed adjacent to each other and said rams are vertically disposed within each lifting means.
 4. A device as claimed in claim 1 in which the hydraulic rams are connected between adjacent sections.
 5. A device as claimed in claim 1 wherein said lower support frame and said upper lifting frame have four rod members extending through the central pivot points of four pairs of cross-levers forming one section of one part of the framework, said rods being adapted to allow contraction and expansion of the framework.
 6. A device as claimed in claim 5 in which the rods are slideably mounted at the central pivot points of said four pairs of cross-levers.
 7. A device as claimed in claim 1 in which said framework is located on the base and includes a booster hydraulic ram mounted on said base extending into abutment with said platform when said fRamework is in the retracted position.
 8. A device as claimed in claim 7 in which the lower outer extremities of the cross members forming the lower section of the framework are disposed on rollers arranged to move in diagonal channels across the base on extension and retraction of said framework.
 9. A device for lifting a load comprising a platform fro supporting said load and a vertically extensible framework for supporting said platform, said framework being formed from a plurality of interconnected parts, each said part of the framework being formed from a plurality of sections, and each said section being formed from first, second, third and fourth pairs of cross-levers pivotally connected at the center thereof, said first and third pairs of cross-levers being spaced parallel and pivotably connected at the outer extremities thereof to the outer extremities of the second and fourth pairs of cross-levers which are also spaced and parallel, thereby to form said framework; lifting means disposed within each of said parts of the framework, each of said lifting means including frame means connected to the central pivot points of pairs of cross-levers forming a section of one part of the framework, and to the central pivot points of pairs of the cross-levers froming another section of said one part of the framework said frame means allowing contraction and expansion of the framework; and vertically disposed ram means pivotably connected in said frame means to cause, on actuation of said ram means, vertical displacement in said frame means to extend or retract the framework and means to allow the outer extremities of the pairs of cross-levers at the top and bottom of said framework to move diagnoally with respect thereto when said framework is extended or retracted.
 10. A device as claims in claim 9 in which the frame means is connected to the central pivot points of opposite pairs of cross-levers forming a section of each part of the framework.
 11. A device as claims in claim 9 in which the frame means is connected to the central pivot points of four pairs of cross-levers forming a section of each part of the framework. 